Rock-drill bit.



M. A. KNAPP.

1100K DRILL BIT. APPLICATION FILED JULY 31, 1911.

1,1 1 8,292.. Patented Nov. 24, 1914.

. dinal section throughthe axis of the bit and MOSES ARTHUR- KNAPP, OFOAKLAND, CALIFORNIA.

ROCK-DRILL BIT.

Specification of Letters Patent.

Patented Nov. 24, 1914.

Application filedJ'uly 31, 1911. Serial No. 641,592.

To all whom it may concern:

Be it known that I, Moses ARTHUR KNAPr,

a citizen of the United States, and resident of Oakland, California,have invented a new and useful Rock-Drill Bit; and I do declare thefollowing to be a full, clear, and exact description of the invention,such as will en able others skilled in the art to make and use the same,reference being had to the accompanying drawings.

My invention relates to the class of rock drills and has for its objectthe provision of a hollow shanked, solid ended, eccentric pointed, rockcutting drill bit through and along which water can be passed to thefront end.

To this end my invention consists in the combination in a rock drill bitof an eccentric point on an elongated prismatic drill head, a hollowshank and a groove on one side of said drill head communicated by adrilled hole with said hollow in the drill shank.

It also consists in means for partially closing said groove, and in thespecific form of the end cutting edges of the bit; all of which is'fully shown in the accompanying drawm s.

%igure 1 is a view of the drill bit on the side having the groove. Fig.2 is a longituthrough said groove. Fig. 3 is a cross-section through thehollow shank and'its lug.

Fig. 4 is a cross-section through said drilled hole. Fig. 5 is across-section through the middle of the bit. Fig. 6 is an end view ofthe bit showing the arrangement of the cutting edges.

Referring, now to Figs. 1 and 4, the prismatic head of the bit isbounded by the lo'ngitudinal prismatic faces 1'23, 41, 42, 43. 20 is theeccentric point of the bit lying nearer the face 42 than to the face 2.It terminates in the point 5.

6, Figs. 1, 2 and 5, is the groove inthe face 2, lying between theprismatic edges 1214 and 13-15.

In Figs. 1, 2, 3 and 4, 8 is the drilled hole communicating the hollow9-10 in the shank 4 with the rearward end of the groove 6. 7 is thearch, passing from the rearward end of edge 14-12 to the rearward end ofedge 15-13, and closing the rearward portion of the groove 6. 11 is thegroove onthe drill point. Y

In Figs. 4, 5, and 6, the bit is shown inclosed in the drill holebounded by the circle 31, 32, 33, 34, 35. Arch 7 and edges 13 15 and1214 are shown as fitting closely against the sides of the drill hole.In Figs. 1, 2, and 6 are shown the end cutting edges of the bit. Theseconsist of "two sets ofedges; first, those on the eccentric point 20,radiating from the apex 5 to the points 2122, 23, 24, 25, 26 and 27,lying principally on the-side of the eccentric point 20 nearest thesides of the prism. The grooves between these edges are open near theapex to allow passage of water. The second set of end cutting edges runbetween points 17 and 15, 15 .and 19, 18 and 14, and 14 and 16, Figs. 1,2 and 6.

'No. 28, Figs. 1, 2 and'5-is a metal strip in serted in the rearwardportion of the groove 6; filling the outer portion of the groove andforming a closed passage of said groove for the length of the strip.This strip is inserted in the form of an arch resting on shoulders inthe groove, and is-swaged into place.

This drill bit is designed especially to be used with hammer drillsprovided with pressure cylinders or other means of holding the bitsquite firmly against the bottom of the drill hole. The action of such aneccentric pointed bit when rotated in the drill hole is to cut a holelarger than itself, by keeping the eccentric point practically in thecenter of the conical end of the drill hole. It follows. that the sideof the drill head opposite I the eccentric point is held against theside of the drill hole. Such being the case, the groove 6, and the spacebetween the face 2 and the wall ofthe drill hole at 35 and the arch 7,together with the drilled hole 8 and the hollow 910 in the shank, form acontinuous passage way for the water or air current used to clear thedrill-hole, from the rear of the drill bit to its cutting end. The headof'the drill bit is left solid and may be swaged into shape whensharpened.

The action of the cutting edges. is as follows: The edges on the sidesof the eccentric point 20 cut a conical hole, leaving a narrow rockshelf between such conical hole and the sides of the drill hole. This iscut down by the edges 1715, 15-19, 1814 and 14 16. As the dulling ofthese last named edges at points 15 and 14 would cause the loss of sizeof the drill hole unless otherwise 1214 and 1315 are sharpened andhardened near their forward end on the side opa central hollow close tothe front end of a t ll bit of this general character owing to thenecessity of swaging the bit every time it is sharpened, this ditlicultyis entirely avoided by use eta solid ended drill bit in which a grooveheld against the side oi the drill hole serves as a water or air passagein place of a central hollow in the metal of the drill bit head.Further, it is quite easy to weld a new end on bits of this character,while the welding 9t hollow steel is very dificult. The easily removablestrip 28 is used only in clayey ground which clogs the groove 6 when thebit is rotated.

A second advantage of this form of bit lies in the shovel shaped cuttingedges on the'end of the bit on the side opposite the eccentric point. itis quite necessary to have edges at this point to cut down the rockshelf mentioned. Edges extending inwardly from the points ld and 15, asdo the edges from points 21, 23, 25 and -27, have 'rela tively verysmall edges edective on the narrow rock shelf and wear down rapidly. Theshovel edges here shown give 5 or 6 times the edective cuttin edge as dosuch in wardly extending e ges. Also the wearing away of the sidecutting edges near points l4'and 15 keeps the shovel edges quite sharpuntil the other end cutting edges are dulled.

Having thus described my invention, what I claim as new and desire toprotect by Letters Patent is:

1. ln a rock cutting drill bit having an eccentric point and having ahollow shank, and in combination withsaid eccentric point and saidhollow shank, an elongated head of said drill bit having a longitudinal.oove'along the side of said head of said rill bit on the side of saiddrill bit head opposite said eccentric point; said groove being 0 en atthe cuttingend of said drill bit bee and being closed at the rearwardend of said I oo've; said hollow in said hollow shank eing communicatedwith said groove by means of a hole through the metal of said drill bithead.

2. In a rock cutting drill bit having an eccentric point and having ahollow shank; and in combination with said hollow shank and saideccentric point a drill bithead of a generally prismatic form having alongitudinal groove lying between two longitudinal ed es of saidprismatic form on the side .0 said drill bit head opposite saideccentric point; said groove being c en at the cutting end of said drillhit an being closed by a metal arch at the rearward end masses of saidgroove; said arch being of apprentimately the same curve as thecircumscribing cylindrical surface of said prismatic form; said hollowin said hollow shank be -point; side cutting edges adapted to cut theside of the drill hole and placed on the side of said elongated headopposite said eccentric point; cutting edges formed on the forward endsof the side planes of the bit on the side opposite said eccentric point,and lying between said side planes and planes directed across the axisof said drill bit head.

4. In a rock cutting drill bit, having an elongated head of a generallyprismatic form and having a projecting end point provided with cuttingedges and placed eccentrically with respect to the axis of said drillbit; and in combination with said elongated head and said projectingpoint, cutting edges parallel to the axis of the drill, and placed onthe side of said drill bit head opposite said eccentrically placedprojecting. point; and other cutting edges on the end of said drill bitand formed in side planes of said prismatic form on point placed on theend of said bit and ec-,

centrically with respect to the axis of said prismatic form; cuttingedges adapted to cut the sides of the drill hole, laced on the side ofthe bit opposite to sai projecting point, and cutting edges on the endof said bit, and on the side of the bit opposite to said eccentricpoint, which do not extend beyond the extension of the side planes ofsa1d prismatic form.

6. In a rock cutting drill bit having a projecting end portion, placedeccentrically with respect to the center of the end of said bit, andhaving cutting edges extending from the apex of said projecting point tothe side of the bit nearest to said eccentrically placed projectingpoint; cutting edges adapted to cut the sides of the drill hole, andplaced on the side of the bit farthest from said projecting point, andcutting edges on the forward end of said bit extending inwardly from theside of the bit farthest from said projecting point; said last namedcutting edges being at approximately right angles to the longitudinalaxis of the drill bit.

tee

7. In a rock cutting drill bit having an elongated prismatic form, aprojecting point on the end of said bit arranged eccentrically withrespect tothe axis 0' said prismatic form, cutting edges on saidprojecting point,-

gated prismatic form.

'8. In a rock cutting drill bit having an eccentric point and agenerally cylindrical shank, and in combination with said eccentricpoint and said generally cylindrical shank an elongated head of saiddrill bit having a longitudinal groove along the side of said head ofsaid drill bit on the side of said drill bit head opposite saideccentric point, and means of closing said groove at its rearward end;said groove being open at the cutting end of said drill bit head, saidgroove at its rearward end being communicated by means of. a passagebeneath said closing means with an inclosed passageway extending fromthe front end to the rearward end of said shank.

MOSES ARTHUR KNAPP.

Witnesses: Y Y

J. E. Lunovioi,

GIRARD F. RICHARDSON.

